Examine source code of CarbonGuru

{
  "manifest_version": 2,
  "name": "CarbonGuru",
  "description": "Know your carbon footprint. Act on it instantly.",
  "version": "1.7.24.2465",
  "browser_specific_settings": {
    "gecko": {
      "id": "carbonguru@carbonguru.io",
      "data_collection_permissions": {
        "required": [
          "personallyIdentifyingInfo",
          "browsingActivity",
          "websiteContent",
          "authenticationInfo"
        ],
        "optional": []
      }
    }
  },
  "permissions": [
    "activeTab",
    "tabs",
    "storage",
    "cookies",
    "https://carbonguru.io/*",
    "https://*/*",
    "menus"
  ],
  "background": {
    "scripts": [
      "purify.min.js",
      "oauth.js",
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*"
      ],
      "js": [
        "purify.min.js",
        "gmail-detector.js",
        "gmail-selection-detector.js",
        "gmail-integration.js",
        "floating-tile-gmail.js",
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_end"
    },
    {
      "matches": [
        "https://*/*"
      ],
      "exclude_matches": [
        "https://mail.google.com/*"
      ],
      "js": [
        "purify.min.js",
        "selection-detector.js",
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_action": {
    "default_title": "CarbonGuru",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "web_accessible_resources": [
    "icons/*",
    "fonts/*"
  ],
  "incognito": "not_allowed",
  "content_security_policy": "script-src 'self'; object-src 'self'"
}